Hydraulic pump



Aug. 23, 1960 Filed April 12, 1957 T. R. STOCKTON 2,949,860

HYDRAULIC PUMP 2 Sheets-Sheet l l d/Ve Z Syria! INVENTOR. 71 an: R 5+0: Khm

BY W 4.-

T. R. STOCKTON HYDRAULIC PUMP Aug. 23, 1960 2 Sheets-Sheet 2 Filed April 12, 1957 United States Patent HYDRAULIC PUMP Thomas R. Stockton, Northville, Mich., assignor to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Apr. 12, 1957, Ser. No. 652,459

17 Claims. (Cl. 103-136) My invention relates generally to an improvement in the art of rotary fluid pumps and more particularly to an eccentric rotor pump having inherent discharge pressure regulating features. The improved pump of my instant invention is particularly adapted to be used with a fluid pressure control system for an automatic, multiple speed, power transmission mechanism of the automotive type although I contemplate that it may have other adaptations as well.

According to a principal feature of my invention, I have provided a rotary pump comprising a circular casing and a rotor disposed within the casing in eccentric relationship therewith. A plurality of radial slots are formed in the rotor within which loosely fitting rollers are situated, said rollers acting as fluid pumping members which correspond to the vane elements of a conventional vane pump or to the Slipper elements of a slipper type pump. The rollers are adapted to move radially within their associated slots and to contact the circular wall of the surrounding casing.

The use of rollers in this fashion makes possible many manufactluring advantages which are not inherent in conventional vane or slipper pumps. For example, the radial slots Within which the rollers are situated and the rollers themselves need not be held to close manufacturing tolerances thus making cost saving, high production manufacturing techniques practical.

According to a principal feature of my invention, I have provided a means for subjecting the radially inward side of each of the rollers to fluid control pressure thereby urging the rollers into sealing contact with the inner wall of the casing.

The magnitude of the fluid pressure on the radially inward side of the rollers may be regulated to provide a variation in the discharge pressure of the pump for any given driving speed of the rotor.

Accord-ing to one embodiment of my invention, the control pressure may be varied in magnitude in accordance with the speed of rotation of the rotor. This latter characteristic adapts the pump for use as a speed sensing device, the discharge pressure being a function of the speed of rotationpf the rotor.

The provision of an improved rotor pump of the type above described being -a principal object of my invention, it is a further object of my invention to provide a roller type pump wherein means are provided for subjecting the radially inward side of the rollers to an independent control pressure thereby regulating the ratio of the pressure in the intake and discharge ports, said control pressure being regulated by an independent regulating device which in turn may be responsive to one or more control parameters.

It is another object of my invention to provide, a roller type pump of the type above set forth wherein the recesses on the inward side of the rollers may be subjected to a control pressure which in turn may be regulated by a valve controlled exhaust passage interconmeeting the region within which the control pressure is effective with a low pressure portion of the fluid circuit.

It is a further object of my invention to provide an improved pump of the type set forth in the preceding object wherein a centrifugally operated valve element may be used to control the degree of restriction of the exhaust passage thereby providing a discharge pressure which is a function of the speed of rotation of the ro- [01.

It is a further object of my invention to provide an improved speed sensing pump of the type above set forth wherein means are included for overruling the speed sensitive characteristics and to adapt the pump for maximum discharge pressure at any given rotor speed.

It is a further object of my invention to provide a rotor pump of the type above described wherein the rotor is eccentrically positioned within the casing to pro vide a minimum clearance between the rotor and the casing at a point intermediate the cutoff edge of the discharge port and the leading edge of the intake port, said cutoff and leading edges being spaced at a distance at least as great as the distance between two adjacent rollers thereby enabling the rollers to effectively seal the high pressure region from the low pressure region of the pump.

It is a further object of my invention to provide a rotary speed sensitive pump of the type above set forth wherein means are included for varying the regulating characteristics of the centrifugally operated valve element to produce any of several desired speed governor characteristics.

For the purpose of particularly describing the principal features of my instant invention, reference may be made to the accompanying drawings wherein:

Figure 1 is a longitudinal cross sectional view ofa roller type pump incorporating certain novel features above set forth;

Figure 2 is a transverse cross sectional view of the pump assembly of Figure 1 taken along section line 2-2 of Figure 1;

Figure 3 is a transverse cross sectional view of one embodiment of my invention and it corresponds to the cross sectional view of Figure 2. This view shows a means for regulating the control pressure acting on the radially inward side of each of the rollers; and

Figure 4 is a graphical representation of the variation in discharge pressure with rotor speed which may be obtained with the pump of Figure 3.

Referring first toFigure 1, the pump is comprised of a casing having two portions 10 and 12 situated in jux-. taposed relationship and defining a pump cavity 14 of circular configuration. A rotor 16 is eccentrically positioned within the cavity 14 and a predetermined clearance may be provided between the sides of the rotor 16 and the adjacent walls of the casing portions 10 and 12 to permit rotation of the rotor 16 within the cavity 14. The rotor 16 is formed with a circular central opening 18 having a flat 20 for accommodating a driving shaft, not shown. Annular grooves 22 and 24 may be formedon opposite sides of the rotor 16, said grooves encircling the axis of the rotor 16. A plurality of radial slots 26 is formed in the rotor 16, as best seen in Figures 2 and 3, said slots being adapted to receive rollers Q8. By preference, the slots 26 are seven in number and a roller 28 is positioned in each slot with a predetermined tolerance to permit radial movement of the rollers during operation. As best seen in Figure 1, the rollers 28 are substantially equal in width to the width of the rotor 16 and they may be tubular in form as indicated. The rollers 28 may be formed of standard stock material and a minor amount of finish machining is required during manufacture.

The radial depth of the slots 26 is at least as great as the outside diameter of the rollers 28 thereby permitting the rollers 28 to move from the position shown on the lower side of the view of Figure 2 to the position shown on the upper side of the same view. Ihe lower portion of each of the slots 26 communicates with the annular grooves 22 and 24.

As best seen in Figure 2, the cavity 14 is cylindrical in shape and it communicates with the discharge port 30 and the intake port 32, the former being shown in part at, the lower portion of Figure 1. Discharge port 30 is arcuate in shape and it extends from a leading edge 34 to a cutoff point located at a cutoff edge 36, the direction of rotation of the rotor being indicated by the directional arrow R. Similarly, the intake port 32 is ercuate in shape and it extends from the leading edge 38 to the cutoff point located at a cutoff edge 40. When one roller 28 reaches the cutoif edge 40, it begins to pump fluid under pressure. By the time this same roller reaches the leading edge 34 of the discharge port 30, an adjacent roller 28 will have reached the cutoff edge 40 thereby preventing any surging of fluid pressure across the working area from the discharge side of the pump to the intake port. Similarly, the arcuate distance between the edges 36 and 38 of the discharge port and the intake port respectively is at least as great as the arcuate distance between two adjacent rollers 28 thereby permitting the rollers to form an effective seal between the discharge and intake ports. I contemplate that the clearance between the rotor 16 and the cylindrical wall of the cavity 14 will be at least .010 at the point of minimum clearance between the edge 36 of the discharge port 30 and the edge 38 of the intake port 32.

I have schematically illustrated in Figure 2 a control pressure passage 42 extending from the annular groove 24 to a control pressure regulating device 44. Control pressure may be supplied to the annular grooves 22 and 24 and to the region on the radially inward side of the rollers 28 through the passage 42, the regulating device 44 being adapted to regulate the magnitude of this pressure in accordance with variations in any appropriate control parameter.

The discharge port 30 may communicate with a dis charge pressure supply passage 46 as schematically illustrated in Figure 2 and this in turn may communicate with appropriate regulating and metering valve elements schematically designated by numeral 48,. said passage 46 and control elements 48 forming a portion of a complete control system for an automatic transmission or the like.

It is thus apparent that the discharge pressure will be determined by the magnitude of the centrifugal force acting on the rollers 28 in accordance with the following relationship:

PD=2PO+% s where P =Disch. press.

P =Suction press.

P =Contro1 press. F =Centrifugal force of roller A =Projected area of slot or roller If the control pressure P undergoes variations during operation, the discharge pressure will vary accordingly. Since the control pressure acts over the entire diameter of the rollers 28, the factor 2 appears in the above equation before the symbol P By way of contrast, the discharge pressure on the left side of the rollers and the static pressure on the right side thereof each acts over only one half of the diameter of the rollers 28. If it is assumed that the static pressure is substantially zero gauge, maximum discharge pressure will be obtained when P +F equals one half the maximum discharge pressure. When the pressure force on the rollers 28 due to the discharge pressure tends to exceed the opposed radially outward force due to the control pressure and the centrifugally operated pressure acting on the rollers 28, the discharge pressure will depress the working rollers within their associated slots thus permitting a portion of the discharge fluid to bypass into the intake side of the pump. The discharge pressure capacity of the pump is thus determined by the combined influence of the control pressure and the centrifugal forces. The control pressure may be varied from a minimum value up to that value which corresponds to the maximum discharge pressure during operation.

Referring next to Figure 3, I have illustrated an alternate arrangement for producing a variable control pressure in the region radially inward of the rollers 28. the corresponding parts of the embodiments of Figures 2 and 3 being designated by common reference characters. A branch passage 50 extends from the discharge passage 46 to a valve member 52, said valve member controlling communication between passage 50 and a low pressure region of the fluid system. The branch passage 50 is formed with a pair of spaced, precalibrated restrictions or orifices 54 and 56 and another branch passage 58 interconnects the annular groove 24 with the branch passage 50 at a point intermediate the orifices 54 and 56. The valve member 52 may assume either a fully opened position or a fully closed position thereby alternately opening and blocking passage 50. If it is assumed that the valve member 52 is in the open position, the static pressure on the downstream side of the orifice 56 will be substantially zero gauge. It is thus apparent that the static pressure in the branch passage 50 at any point between the orifices 54 and 56 will be substantially one half the discharge pressure P the sizes of the orifices being equal. At any pump speed the fluid pressure which exists in the region radially inward of the rollers 28 will be equal to one-half of the discharge pressure since this region is in continuous fluid communication with the branch passage 50 intermediate the orifices 54 and 56.

As previously mentioned, the radially inward side of the slots 26 and the annular grooves 22 and 24 are in continuous fluid communication and the control pressure acting in this region is caused to be exhausted through an exhaust passage 60 preferably communicating with one of the radial slots 26 as indicated in Figure 3. The exhaust passage 60 extends to a radial bore 62 formed in the rotor 16 and it communicates with a passage 64 located in a plug 66 secured within the bore 62. The passage 64 is progressively restricted by a valve element 68 situated in a radially inward part of the bore 62, said valve element 68 preferably having a conical nose 70 which may cooperate with the end of the passage 64. A suitable valve spring 72 may be provided as indicated for urging the valve element 68 into a passage closing position and it may be seated upon a pump rotor driving shaft received through circular opening 18.

It is apparent from an inspection of Figure 3 that control pressure acting on the rollers 28 will increase as the speed of rotation of the rotor 16 increases since the centrifugal force acting on valve 68 tends to restrict passage 64, the restriction being greater at higher speeds than at lower speeds. Since the discharge pressure is in turn a function of the magnitude of the control pressure, as previously explained, the discharge pressure will be determined by the following relationships:

s'iov) on PD Av As s where P =Disch. press.

P =Suction press.

P =Control press. F Centrifugal force of roller A =Projected area of slot or roller F =Centrifugal force of valve A =Valve seat area F =Forceof valve spring.

' It therefore follows that the magnitude of the discharge pressure will be an indicator of the magnitude of the rotor speed. This feature makes this pump arrangement particularly adaptable for use as a fluid governor for an automatic power transmission and it may be conveniently mounted on the power output tail shaft of the transmission. The discharge pressure of the pump may be utilized in the control circuit as a speed sensing pressure for initiating the operation of the control valve elements to establish the various shift sequences. If it is desired to use the pump arrangement of Figure 3 as a source of line pressure for the control valve system during an emergency operation-for example, when a push start is desired-the valve member 52 may be moved to a closed position thereby causing the pressure in the branch passage 50 intermediate the orifices 54 and 56 and the pressure in the region on the radially inward side of the rollers 28 to immediately assume a value equal to the magnitude of the discharge pressure. Thisimmediately increases the capacity of the pump to its maximum value and the pump is thus convertedfrom a speed sensing governor to an effective fluid pressure source. After the engine is started by means of a push start, a conventional engine driven fluid pump may then assume the function of supplying the control circuit with line pressure and the valve 52' may then again be moved to an open position thus again converting the pump arrangement of Figure 3 into a vehicle speed governor mechanism.

For purposes of illustration, we have shown in Figure 4 a graphical representation of the variation in discharge pressure for the pump arrangement of Figure 3 as the rotor speed increases. If a purely parabolic relationship is desired, the valve spring 72 may be removed and the resulting characteristic will be similar to that shown on the lower curve of Figure 4. If it is desired to make the governor mechanism more sensitive at lower vehicle speeds, an appropriately calibrated valve spring 72 may be used and the resulting curve will be somewhat similar to the upper curve appearing in Figure 4. The valve spring 72 will, under these conditions, maintain the passage 64 closed until the control pressure below the rollers 28 reaches a predetermined value at which time the valve element 68 becomes unseated. The variation in discharge pressure with rpm. prior to the time the valve element 68 becomes unseated will be quite sensitive and the slope of the corresponding portion of the characteristic curve will be very steep. The point at which the valve element 68 becomes unseated is illustrated in Figure 4 by numeral 74. Thereafter, the slope of the characteristic curve will be substantially less, said curve being parallel to the lower curve previously described as shown in Figure 4.

Although I have particularly described certain novel features of a preferred embodiment of my invention, I contemplate that variations thereto may be made by persons skilled in this art without departing from the scope of my invention as defined by the following claims.

I I claim:

l. A rotary pump comprising a cylindrical rotor, a casing, a substantially cylindrical bore formed in said casing with a diameter greater than the diameter of said rot'or, said rotor being eccentrically mounted for rotation within said bore, a plurality of radial recesses formed in the periphery of said rotor, a cylindrical 'depth thereof being at least as great as the diameter of its associated roller, a fluid intake port and a fluid discharge port communicating with said bore at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communirating with each of said'recesses on the radially inward sides of said rollers, a branch passage extending from, the region of said discharge port to a low pressure region, a pair of precalibrated orifices formed in said branch passage, and passage means for connecting said annular groove and said branch passage at a point intermediate said orifices. I

2. A rotary pump comprising a cylindrical rotor, a casing, a substantially cylindrical bore formed in said casing with a diameter greater than the diameter of said rotor, said rotor being eccentrically mounted for rotation within said bore, a plurality of radial recesses formed in the periphery of said rotor, a cylindrical roller situated in each of said recesses, the circumferential width of said recesses being substantially equal to the diameter of the associated rollers and the radial depth thereof being at least as great as the diameter of its associated roller, a fluid intake port and a fluid discharge port communicating with said bore at angularly spaced locations, an annular groove formed on atleast one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said rollers, a branch passage extending from the region of said discharge port to a low pressure region, a pair of precalibrated orifices formed in said branch passage, passage means for connecting said annular groove and said branch passage at a point intermediate said orifices, and valve means including portions located in said branch passage at a point downstream from said orifices for selectively blocking said branch passage and for opening the same to said low pressure region.

3. A rotary pump comprising a cylindrical rotor, a casing, a substantially cylindrical bore formed in said casing with a diameter greater than the diameter of said rotor, said rotor being eccentrically mounted for rota tion within said bore, a pluralityof radial recesses formed in the periphery of said rotor, a cylindrical roller situated in each of said recesses, the circumferential width ofsaid recesses being substantially equal to the diameter of the associated rollers and the radial depth thereof being at least as great as the diameter'of its associated roller, a fluid intake port and a fluid discharge port communicating with said bore at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said rollers, a branch passage extending from the region of said discharge port to a low pressure region, a pair of pre calibrated orifices formed in said branch passage, passage means for connecting said annular groove and said branch passage at a point intermediate said orifices, an exhaust passage formed in said rotor between said an nular groove and a low pressure region and a metering valve element mounted within said rotor in the region of said exhaust passage, said valve element being subjected to centrifugal force as said rotor is rotated and adapted to progressively restrict said exhaust passage.

4. A rotary pump comprising a cylindrical rotor, a casing, a substantially cylindrical bore formed in said casing with a diameter greater than the diameter of said rotor, said rotor being eccentrically mounted for rotation within said bore, a plurality of radial recesses formed in the periphery of said rotor, a cylindrical roller situated in each of said recesses, the circumferential width of said recesses being substantially equal to the diameter of the associated rollers and the radial depth thereof being at least as great as the diameter of its associated roller, a fluid intake port and a fluid discharge port communicating with said bore at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said rollers, a branch pas sage extending from the region of said discharge port-t9 a lovs pressure region, a pair of precalibrated orifices formed in said'branch passage, passage means for connecting said annular groove and said branch passage at a point intermediate said orifices, an exhaust passage providing communication between said annular groove and a low pressure region and a radially movable valve element carried by said rotor with a portion thereof cooperating with'said exhaust passage, said valve element being adapted to restrict said exhaust passage when subjected to centrifugal force due to the rotation of said rotor, the eflective pressure in said annular passage and in said recesses on the radially inward side of said rollers thereby being a function of the speed of rotation of said rotor.

5. A rotary pump comprising a cylindrical rotor, a casing, a substantially cylindrical bore formed in said casing with a diameter greater than the diameter of said rotor, said rotor being eccentrically mounted for rotation within said bore, a plurality of radial recesses formed in the periphery of said rotor, a cylindrical roller situated in each of said recesses, the circumferential width of said recesses being substantially equal to the diameter of the associated rollers and the radial depth thereof being at least as great as the diameter of its associated roller, a fluid intake port and a fluid discharge port communicating with said bore at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said rollers, a branch passage extending from the region of said discharge port to a low pressure region, a pair of precalibrated orifices formed in said branch passage and means for providing communication between said annular groove and said branch passage at a point intermediate said orifices, an exhaust passage connecting said annular groove and a low pressure region, a radially movable valve element carried by said rotor with a portion thereof cooperating with said exhaust passage, said valve element being adapted to restrict said exhaust passage when subjected to centrifugal force due to the rotation of said rotor, the effective pressure in said annular passage and in said recesses on the radially inward side of said rollers thereby being a function of the speed of rotation of said rotor, and a valve spring acting on said valve element and adapted to urge the same in a radially outward direction into an exhaust passage closing position thereby altering the metering characteristics of the same.

6. A rotary pump comprising a cylindrical rotor, a casing, a substantially cylindnical bore formed in said casing with a diameter greater than the diameter of said rotor, said rotor being eccentrically mounted for rotation within said bore, a plurality of radial. recesses formed in the periphery of said rotor, a cylindrical roller situated in each of said recesses, the circumferential width of said recesses being substantially equal to the diameter of the associated rollers and the radial depth thereof being at least as great as the diameter of its associated roller, a fluid intake port and a fluid discharge port communicating with said bore at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said rollers, a branch passage extending from the region of said discharge port to a low pressure region, a pair of precalibrated orifices formed in said branch passage, means for providing communication between said annular groove and said branch passage at a point intermediate said orifices, an exhaust passage connecting said annular groove and a low pressure region, a radially movable valve element carried by said rotor with a portion thereof cooperating with said exhaust passage, said valve element being adapted to restrict said exhaust passage when subjected to centrifugal force due to the rotation of said .8 rotor,"tlre effective pressure in said annular passage and in said recesses on the radially inward sides of said rollers thereby being a function of the speed of rotation of said rotor, and valve means including portions disposed in said branch passage and situated on the downstream side of said orifices for selectively blocking said branch passage and for opening :the same to said low pressure region thereby enabling the pump to alternately function as a rotor speed sensing mechanism and as a positive displacement fluid pressure source.

7. The combination as set forth in claim 1 wherein said orifices are of equal size.

8. A rotary pump'comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, a pumping member situated in each recess, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, a branch passage extending from a high pressure region of said pump to a low pressure region thereof, a pair of precalibrated orifices formed in said branch passage, and passage structure formed in part in said rotor including a portion connected to said branch passage at a location intermediate said orifices and extending to said recesses for subjecting the radially inward sides of said pumping members to fluid pressure.

9. A rotary pump comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, a pumping member situated in each recess, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, a branch passage extending from a high pressure region of said pump to a low pressure region thereof, a pair of precalibrated orifices formed in said branch passage, passage structure formed in part in said rotor including a portion connected to said branch passage at a location intermediate said orifices and communicating with said recesses for subjecting the radially inward sides of said pumping members to fluid pressure, and valve means including portions located in said branch passage at a location downstream from one of said orifices for selectively blocking said branch passage and for opening the same to said low pressure region.

10. A rotary pump comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, a pumping member situated in each recess, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, a branch passage extending from a high pressure region of said pump to a low pressure region, a pair of precalibrated orifices formed in said branch passage, passage structure formed in part in said rotor including a portion connected to said branch passage at a location intermediate said orifices and communicating with said recesses for subjecting the radially inward sides of said pumping members to fluid pressure, an exhaust passage defined in part by said rotor extending from the radially inward region of said recesses to a low pressure exhaust region, and a metering valve element communicating with said exhaust passage, said metering valve element being rotatable with said rotor and subjected to centrifugal force to progressively restrict said exhaust passage.

11. A rotary pump comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, a pumping member situated in each of said recesses, said pumping members being adapted for radial movement in said recesses with respect to said rotor, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said pumping members, a branch passage'extending from'the region of. said discharge port ag ressto a low pressure region, a pair of precalibrated orifices formed in said branch passage, passage means for connecting said annular groove and said branch passage at a: locationintermediate. said orifices, an exhaust passage extending from said annular groove to a lower pressure region, and a movable valve element carried by said rotor with ,a portion thereof cooperating with said exhaust passage, said valve element, being adapted to restrict said exhaust passage when subjected to centrifugal force due to. the rotation of said rotor, the effective pressure in said discharge port ,and in said recesses on the radially inward sides of said pumping members thereby being a function of the speed of rotation of said rotor.

12. A- rotary pump comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, a pumping member situated in each of said recesses, said pumping members being adapted for radial movement in said recesses with respect to said rotor, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said pumping members, a branch passage extending from the region of said discharge port to a low pressure region, a pair of precalibrated orifices formed in said branch passage, passage means for connecting said annular groove and said branch passage at a location intermediate said orifices, an exhaust passage extending from said annular groove to a lower pressure region, a movable valve element carried by said rotor with a portion thereof cooperating with said exhaust passage, said valve element being adapted to restrict said exhaust passage when subjected to centrifugal force due to the rotation of said rotor, the efiective pressure in said discharge port and in said recesses on the radially inward sides of said pumping members thereby being a function of the speed of rotation of said rotor, and a valve spring acting on said valve element and adapted to urge the same in a radially outward direction into an exhaust passage closing position thereby altering the metering characteristics thereof.

13. A rotary pump comprising a rotor, a casing, said casing defining a rotor chamber, a plurality of recesses formed in the periphery of said rotor, a pumping member situated in each of said recesses and adapted for radial movement in said recesses relative to said rotor, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, an annular groove formed on at least one lateral side of said rotor, said groove cooperating with said casing to define a circular passage communicating with each of said recesses on the radially inward sides of said pumping members, a branch passage extending from the region of said discharge port to a low pressure region, a pair of precalibrated orifices formed in said branch passage, means for providing communication between said annular groove and said branch passage at a point intermediate said orifices, an exhaust passage connecting said annular groove and a lower pressure region, a movable valve element carried by said rotor with a portion thereof cooperating with said exhaust passage, said valve element being adapted to restrict said exhaust passage when subjected to centrifugal force due to the rotation of said rotor, the effective pressure in said discharge port and in said recesses on the radially inward sides of said pumping members thereby being a function of the speed of rotation of said rotor, and valve means including portions disposed in said branch passage and situated on the downstream side of one of said orifices for selectively blocking said branch passage and for opening the same to said low pressure region thereby enabling the pump to alternately function as a rotor speed sensing mechanism and as a positive displacement fluid pressure source.

14. rotary comprising a rotor, acasing', said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, pumping members situated in each recess, said pumping members being adapted for movement in said recesses relative todistributing fluid pressure to the radially inward region of said recesses thereby urging said pumping members in a generally outward direction, an exhaust passage formed in part insaid rotor interconnecting said radially inward region of said recesses and a low pressure exhaustregion, and a metering valveelement having portions communicating with said exhaust passage, said valve element being urged under the influence of centrifu galforce due to the rotation of said rotor into an exhaust passage restricting direction, the degree of restriction of said exhaust passage and the pressure acting on the radially inward sides of said pumping members thereby being determined by the speed of rotation of said rotor.

15. A rotary pump comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, pumping members situated in each recess, said pumping members being adapted for movement in said recesses relative to said rotor, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, passage means formed in part in said rotor for distributing fluid pressure to the radially inward region of said recesses thereby urging said pumping members in a generally outward direction, an exhaust passage formed in part in said rotor interconnecting said radially inward region of said recesses and a low pressure exhaust region, a metering valve element having portions communicating with said exhaust passage, said valve element being urged under the influence of centrifugal force due to the rotation of said rotor in an exhaust passage restricting direction, the degree of restriction of said exhaust passage and the pressure acting on the radially inward sides of said pumping members thereby being determined by the speed or rotation of said rotor, and a spring element acting on said valve element for normally urging the same in an exhaust passage closing position thereby influencing the metering characteristics of said valve element and the speed-pressure relationship of said pump.

16. A rotary pump comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, pumping members situated in each recess, said pumping members being adapted for movement in said recesses relative to said rotor, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced locations, passage means formed in part in said rotor for distributing fluid pressure to the radially inward region of said recesses thereby urging said pumping members in a generally outward direction, an exhaust passage formed in part in said rotor interconnecting said radially inward region of said recesses and a low pressure exhaust region, a metering valve element having portions communicating with said exhaust passage, said metering valve element being carried by the rotor and urged in a generally radial direction under the influence of centrifugal force in an exhaust passage closing direction, the degree of restriction of said exhaust passage and the pressure acting on the radially inward sides of said pumping members thereby being determined by the speed of rotation of said rotor.

17. A rotary pump comprising a rotor, a casing, said casing defining an internal rotor chamber, a plurality of recesses formed in the periphery of said rotor, pumping members situated in each recess, said pumping members being adapted for movement in said recesses relative to said rotor, a fluid intake port and a fluid discharge port communicating with said chamber at angularly spaced loof said recesses thereby urging said pumping members in a generally outward'direction, exhaust passage means formed in part in said rotor interconnecting said radially inward region of said recesses and a low pressure exhaust region, a metering valve'element having portions 00111 municating with saidexhaust passage, said metering valve element being carried by the rotor and urged in a generally radial direction under the influence of centrifugal force in an exhaust passage closing direction, the degree of restriction of said exhaustpassage and the pressure acting on the radially inward sides of said pumping members thereby being determined by the speed of rotation of said rotor, and spring means for normally 'urging said valve element in a radially outward direction to supplement the centrifugal force acting on said valve element.

References Cited in the file of this patent UNITED STATES PATENTS Guinness May 23, Kendrick Sept. 16, Kendrick May 18, Tweedale Nov. 2 6, Ferris -Mar. 10, Baugh etali Mar. 17, Kovach Oct. 4, Gardiner Mar. 27, Pettibone Feb. 26,

FOREIGN PATENTS Great Britain Oct. 27, 

